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Plastic bending -using FTU
The simple (and most conservative way) to calculate FTB is to use the following formula: FTB = FTU + (1-k)*FTY There is, however, another way to calculate FTB using a longer method out of the Boeing Design Manual (1967). I've attached an image using from a MathCAD document showing this...- Allanon81
- Post #5
- Forum: Aircraft engineering
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Analysis of Sandwich Panels
You may have another issue to consider... if the out-of-plane shear is due to bending, then the shear flow around the panel will cause an in-plane shear stress. Thus, you can't go over the in-plane allowable given by the core anyway.- Allanon81
- Post #8
- Forum: Aircraft engineering
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Fuselage Cutouts and Skin Doublers
That's the nice thing about this... I do have the OEM reports with the full FEA. It gives me the stringer end loads and panel shear flow for each piece of the fuse for multiple load conditions... you have no idea what I had to go through to get it... I'm working on sizing the structure now...- Allanon81
- Post #12
- Forum: Aircraft engineering
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Fuselage Cutouts and Skin Doublers
der8110... that was my point... however, where the mod is located, it might interfere a little bit with the forward part of the fairing. That said, it would still be a lot cheaper to add the doubler, trim the fairing a little bit a reinstall. 40818... I've ran into such problems before. We...- Allanon81
- Post #10
- Forum: Aircraft engineering
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Fuselage Cutouts and Skin Doublers
40818, you are correct... this is a VIP business jet. Thanks for the advise... I'm looking into both solutions and providing them both. Thanks for the input!- Allanon81
- Post #7
- Forum: Aircraft engineering
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Fuselage Cutouts and Skin Doublers
It's located in the forward fuselage, but in a pressurized area... so yes, pressure loads will have to be considered as well. I've basically told them the same thing... that it will be cheaper to put an external dblr on the stupid thing and be done with it... it's definitely a lot easier to...- Allanon81
- Post #5
- Forum: Aircraft engineering
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Fuselage Cutouts and Skin Doublers
haha... anything's possible, just mathematically improbable... right? Unfortunately the internal doubler won't work without taking out a large section of frames/stringers. Plus the skin is chem-milled by the OEM to certain thicknesses based on the FEA. When you say to reinforce the next...- Allanon81
- Post #3
- Forum: Aircraft engineering
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Fuselage Cutouts and Skin Doublers
I'm a stress engineer working a particularly challenging/interesting problem. We're working a modification to a CL-605 fuselage where a customer wants us to install a service panel, but wants to avoid the use of external doublers. The cutout in the fuselage would span one frame bay and cut one...- Allanon81
- Thread
- Replies: 14
- Forum: Aircraft engineering
